1. Field of the invention
The present invention relates in general to a multi-valve internal combustion engine having duplicated or tripricated inlet and/or exhaust valves per each cylinder and more particularly to a valve train arrangement used in such a multi-valve engine and having a cam follower adapted to operate two or three valves (inlet or exhaust) in unison.
2. Description of the Prior Art
In a known valve train arrangement for a multi-valve engine, a single cam follower is adapted to operate two valves in unison with a view to reducing the mass of the valve train movable parts thus enabling high RPM engine operation. The cam follower may be arranged so as to pivot upon a lash adjuster as disclosed in Japanese Provisional Patent Publication No. 59-103907.
In order that the two-fingered cam follower is correctly held in contact with the valve stems, it has been proposed to provide the cam follower with a guide means in the form of flanges as disclosed in co-pending U.S. patent application Ser. No. 900,844, filed Aug. 27, 1986 still pending.
With this guide means, the cam follower however has a possibility of being displaced out of position relative to the valve stems when the engine is over-revved due to an errorneous work on the accelerator pedal or the like. This is because under such an engine over-revved condition the cam follower effects a so-called "jumping" or "bouncing action and moves apart from the valve stems by the amount exceeding the height of the flanges, resulting in that the cam follower is movable freely relative to the valve stems, i.e., movable upwardly and downwardly and tiltable laterally while pivoting upon the lash adjuster. When the cam follower is out of position, e.g., when the cam follower is put into a condition in which the guide means is clamped between the cam follower and the valve stems or the cam follower is disengaged from the valve stems, the valve train will be damaged and malfunction.